GO Bond Prop A - Flood Protection and Drainage Update

This update for July 2024 highlights progress on the Proposition A Flood Protection and Drainage Improvements from the 2019 GO Bond. In May 2019 voters approved general obligation bonds allocating $73 million for 21 drainage projects. The bulk of the projects will provide drainage improvements in and around several League City subdivisions.

Six projects have been completed which include the City Wide 2D Modeling, Bay Ridge Ph 3, Oaks of Clear Creek Overland Flow, Bradshaw Ditch/Southeast Detention Pond, Dove Meadows Detention Pond and Bay Colony Area Detention Ponds.

On April 23, 2024, a Public Hearing was held at the City Council meeting to consider a scope change to the GLO project known as North League City Drainage Improvement Projects. The purpose of the hearing was to review the request to decrease the project scope by removing the proposed The Landing, Newport and Ellis Landing, and Brittany Bay Subdivision Drainage Improvements from the larger project. These projects were included as part of the May 2019 General Obligation Bond Referendum. All three were awarded CDBG-DR funding through GLO while the Brittany Bay Subdivision Improvements Project was also awarded a HMGP grant through FEMA. Design of these projects included overflow swale drainage improvements that utilize existing storm sewer outfall easements between residences to provide surface flood relief for adjacent streets to drain into nearby creeks. Staff met with each of the subdivision HOA's as well as property owners of the affected residences to explain the projects and build consensus due to impacts to side and back yards. City staff felt that based on feedback received, it was the consensus of the involved parties that the Brittany Bay, Newport & Ellis Landing, and The Landing drainage improvement projects should not move forward. The motions were passed to revise the scope of the GLO project as well as remove these projects from the Bond. Unspent funds slated for these projects will be reallocated to other drainage projects.

Overall, the status of the program is as follows:

6 Complete

5 Cancelled

3 Currently under construction

6 Currently under design

1 Scheduled for purchase in 2025

Construction

Bay Ridge Phase 2 Pump Station

https://www.leaguecitytx.gov/3445/Bay-Ridge-Flood-Reduction-Phases-I-IV

Phase 2 is the third of four planned projects impacting the Gum Bayou Watershed and the Bay Ridge Subdivision to enter construction. These drainage projects will help with street ponding and reduce the flooding potential during major rainfall events. This project adds capacity to the current detention pond by deepening it and adds a dedicated pump station to pump storm water out of the pond and into Gum Bayou after a major rainfall event. Subdivisions/areas affected include Bay Ridge Area, Hidden Lakes, Whispering Lakes, and Lakes of South Shore.

Pond excavation has been completed as well as construction of the intake, discharge, foundation and walls for the pump station. Pilot channels and slope paving are complete. Pumps and discharge lines have been installed. The generator was delivered and installed in November. TNMP has installed poles for the electrical service along the property. A change order was approved via Council action on February 13, 2024 to relocate the new electrical transformer connection. Due to reevaluation of the project site by the current area TNMP representative, it was determined that the original location in the design plans has limited accessibility if the need arises for future repairs and would need to be relocated. The change order covered the contractor's costs to run additional electrical conduit and wire as well as saw cut pavement and pour a new pad for the transformer. Placement of rip rap at the outfall into the creek near the existing duckbill valve to help reduce sediment buildup was also included in the change order scope. The transformer is slated to arrive in late summer 2024 due to parts shortages in the industry. In preparation for hurricane season, the City trained our operators in early June on manual operation of the pumps and generator in case the station needs to be activated before permanent power is installed.As of now, the pumps can be operated via generator power.

The Meadows Drainage Improvements, Phases I & II

https://www.leaguecitytx.gov/3474/The-Meadows-Drainage-Improvements-Phases

The Meadows Drainage Project will address chronic flooding by providing clear, unobstructed drainage flow along drainage easements in the subdivision. The design includes adding overflow swales, deepening the existing channel, and upsizing the culvert at Smith Lane.

Construction commenced in February 2024. The contractor is finishing up Phase 2 of construction, which included excavation and regrading of ditch RB103-00-00 and outfall improvements between FM 270 and Smith Lane followed by storm sewer improvements at Paintbrush Avenue. The contractor will soon begin Phase 3, which are proposed headwall and concrete box culvert improvements at Smith Lane.

Bay Ridge Subdivision Drainage Improvements Phase 1

https://www.leaguecitytx.gov/3445/Bay-Ridge-Flood-Reduction-Phases-I-IV

Bay Ridge Flood Reduction - Phase 1 Levee Improvements will elevate the front 400' of Bay Ridge Drive, which was determined to be the main risk of flooding from external flood sources. Final design plans have been approved and signed by the city as of August 2023. Due to proximity with the TxDOT ROW a LOSA was required for construction and has been fully executed by the City and State. Plans have been submitted to TxDOT and receipt of the permit is pending.

The advertisement for bid posted in January 2024, and bids opened in February. The construction contract was awarded by City Council on March 26, 2024. The pre-construction meeting was held May 6^th and the construction notice to proceed was issued for May 15th. Due to an adjacent TxDOT project on SH 96, there was a delay in issuing a temporary construction permit. The City's consultant issued an alternative staging plan to TxDOT which was approved the last week of June. The City's contractor should be mobilized by mid-July.

Design

Brief updates of some of the projects in design are below.

Phase 4 of the Bay Ridge Flood Reduction program focuses on Gum Bayou. Proposed culverts at the Columbia Memorial Parkway and League City Parkway were analyzed to determine the appropriate size to reduce ponding and the potential overflows. Hydrology and hydraulics (H&H) studies of Gum Bayou from League City Parkway (SH 96) to Dickinson Bayou were conducted in an effort to provide improvements to allow Bay Ridge Subdivision's detention to drain. Existing Gum Bayou bridges were a part of the hydraulic analysis. This study helped evaluate the flow of water heading towards Dickinson Bayou in order to provide options for drainage improvements for the Gum Bayou Watershed. City staff is currently evaluating potential locations required to meet detention capacity necessary to implement the project. Council has approved moving forward with an agreement to purchase excess regional detention capacity in a development in Texas City which satisfies a large portion of the detention requirement for this project. Potential agreements are currently being negotiated with the Developer and Texas City. Once the location(s) have been nailed down a revised proposal will be requested from the consultant with a revised scope of work.

The Magnolia Creek & Cedar Gully Channel Improvements include modification of Magnolia Creek, Cedar Gully, and related tributaries to be regraded/sized to accommodate for Atlas 14. This is to ensure the drainage of Westover Park, Countryside, Magnolia Creek and Rustic Oaks subdivisions into the system is meeting design standards and does not result in structural flooding within the neighborhoods. Desnagging of the waterways will need to take place with this work. USACE permit comment response letter was submitted October 28, 2022. Additional correspondence was received from the USACE on May 16^th with additional comments. The project team held a teleconference with USACE staff in June to discuss the project as a whole. Comments were addressed and submitted back to the USACE. In July 2023 the USACE issued another public notice for the project. Additional comments and correspondence from reviewing agencies were forwarded to the city and consultant in mid-August. These comments were addressed, and a response sent back to the USACE in September 2023. The drawings are now under review with the USACE.

Design plans and specifications are complete and ready for bid advertisement for the Countryside Subdivision Drainage Improvement. The city held a public meeting with homeowners in September 2022 and based on their recommendations, the City will reevaluate flooding observed and reported after Hurricane Harvey. The city will also clear out debris in the existing outfalls to Magnolia Creek. A meeting with Countryside South Community Association was held on March 8, 2023, to discuss the project scope and answer resident concerns. The City is awaiting a decision from the residents of the subdivision regarding moving forward with the project. If they wish to proceed, the final scope will be dependent on the HOA and resident concurrence with the improvements as proposed or a modified scope thereof.

The Benson Bayou Detention Project - Phase 1 will provide critical detention improvements within the watershed coupled with grade adjustments to the existing bayou in efforts to reduce water surface elevations to benefit the area while ensuring no adverse impact to downstream neighbors. In June 2022 an environmental investigation of a proposed pond site revealed a large number of forested wetlands within the proposed project area. The city directed the consultant to revise the project scope of work and design to remain within the approved budget for the project. The consultant delivered the revised schematic design on July 22, 2022, which included several alternative options to construct the detention basin within a smaller project footprint. City staff has requested that the consultant also explore the possibility of expanding an existing pond in the in the area and constructing a pump station. The report was received and was submitted to engineering for review. The City has reviewed and is determining whether the revised scope of the project is more cost effective, feasible, and within the approved budget.

The FM518 & Wesley Dr Drainage Improvements project focuses improvements on capturing and conveying the stormwater runoff that exceeds the current storm sewer system capacity at the intersection of FM 518 and Wesley Drive. The improvements will include upsizing and installing a new storm sewer system to convey stormwater to Corum Ditch. The project will incorporate current drainage and stormwater design standards. The Texas General Land Office (GLO) approved the AUGF (Authority to use Grant Funds) on February 21st. 100% plans were approved by the City on August 03, 2023. Due to the cost of improvements in the ROW, TXDOT is requiring an Advance Funding Agreement (AFA). The AFA that was presented to City Council and approved on June 25th. PMO has sent TxDOT the documentation that is needed to finalize the AFA. Relocation for CenterPoint gas lines in conflict on the northern TXDOT ROW are complete. Relocation of Comcast utility is currently pending. Coordination between Frontier and contractor will need to take place during construction of the storm sewer to ensure conflicts are resolved during intersection closure. Utilities once exposed, will either be lowered or moved away during construction after exposure.

The Oaks of Clear Creek North Detention Pond will reduce structural and street flooding in the Oaks of Clear Creek Subdivision in conjunction with the improvements from the Oaks of Clear Creek Detention and Deer Ridge Drive Overland Flow Projects. Purchase of land required for the drainage easement is in progress. The consultant is working on the environmental assessment (EA) and cultural resources study. GLO has reviewed and accepted the Environmental Assessment (EA) for Oaks of Clear Creek. The storm sewer route requires an easement along CenterPoint Energy right of way. CenterPoint held an internal meeting to discuss options for the city to install approximately 3100 L.F. of 42-inch box culverts in their corridor and has tentatively approved access for installation in their ROW pending receipt and approval of surveyed easement. The consultant is addressing the City's 60% design comments. 90% plans are on hold due to CenterPoint conflicts.

The Hughes Lane and W. Deats Rd Culvert Modification Project will increase capacity and efficiency of drainage flows through Borden's Gully to I-45. Revised 30% design plans were received in October 2022 and design coordination between the City of League City and City of Dickinson design consultants progressed through April 2023. The City's consultant was given authorization to proceed with 60% design in May 2023. A contract amendment for final design, bid and construction phase services was approved at the October 24th meeting. Additional scope was added to the project to modify plans to eliminate utility conflicts found during design review. New conflicts with existing drainage facilities that encroach into the right-of-way were identified and will require coordination with TxDOT and adjacent property owners. The consultant is incorporating these changes into the 100% design, which is anticipated to be submitted next month.

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